MIT boffins crack fusion plasma snag

Boffins at MIT say they have cracked some tricky problems in the design of power stations running on nuclear fusion, though they hasten to add that many more hurdles remain before fusion energy becomes a reality.

"There's been a lot of progress," says Earl Marmar, head of the Alcator Project at the MIT Plasma Science and Fusion Center (PSFC).

"We're learning a lot more about the details of how these things work."

The Alcator project has its own reactor, and physicists there have been working on several conundrums which have to be solved before the new super-sized international reactor in France (ITER) can even be completed.

In particular, the MIT brains say they have worked out a new and better method for making the unbelievably hot plasma inside the doughnut shaped reactor move around. It has to do that, apparently, in order not to lose all its heat into the vessel walls.

It seems that Yijun Lin and John Rice of MIT have found a way of making the plasma move about by pushing it with radio waves, which will be critical to the operation of the ITER.

"That's very important," Marmar says. "People have been trying to do this for decades."

No plasma circulation "is potentially a showstopper" for ITER, according to Rice. However nobody is exactly sure why the MIT radio-push methods work.

"Some of these results are surprising to theorists," says Lin.

The Alcator team are also proud to announce their development of a cunning noble-gas extinguisher method for quenching troublesome beams of "runaway electrons", which can apparently be an issue in the event of a fusion reactor's magnetic containment fields having a collywobble.

Lin thinks that incorporation of the MIT technology will give the enormous, multibillion-pound ITER a much greater chance of success. "Our results are just in time," he says, as the mighty machine is already half built.

That's obviously very important, because if practical fusion reactors can be developed which put out more power than they need to run, the human race's energy problems are largely over. Unlike the scarce and expensive uranium required for present-day fission reactors, the hydrogen isotopes which would be used for fusion are commonplace and could readily be extracted from seawater.

Clean and abundant fusion electricity, quite apart from rendering the wind/coal/fission power-station debate irrelevant, would also solve the underlying problems of replacing fossil-fuelled transport. No matter whether you favour hydrogen or battery or synthi-petrol made from CO2, very large amounts of energy have to be used.

Indeed, most of the world's troubles actually boil down to energy in the end. Farms in the Third World could easily feed the world's hungry if they had energy-intensive fertilisers and powered machinery: starvation is essentially an energy problem. Water is energy, too - there's no need to worry about how much you use if you can make more out of seawater.

So we should all be hoping that ITER is a success, and cheering on fusion researchers like the MIT Alcator team. ®